Getting rid of Japanese beetles

These beetles are gold with greenish sheen and would have looked nice if  they weren't so destructive.

 http://en.wikipedia.org/wiki/Japanese_beetle

They eat the leaves of fruit bearing trees, roses, cannas and our bonsai (maples, beech, hornbeams).  The easy way to protect the plants  is to use a commercial spray with nasty ingredients (malathion) but husband and I searched for an organic (safer) way to do it.   Traps are out of the question because they will attract more bugs in our area. An online search yielded an interesting suggestion.  Apparently,  having a bucket with some dishwashing liquid and a little bit of water  as the tool to kill these buggers is effective, at least based on our experience.  These bugs start to appear mid-late June  here in our area.  We kept an eye out for the first few bugs which are actually "scouts".  They survey areas and if they find a good one (lots of potential food), they summon more JBs.  So husband and I kept a bucket on hand and did our JB patrols.  Just a light tap on the leaf where these buggers are perched will send them right into the bucket.  Yes, we had a lacy leafed crab apple (15 ft) last year but at least, we didn't have damage in our bonsai. It is still to early too tell if our method reduced the JB number that will be coming to our yard this year (they are usually at their highest numbers mid July). 

JB update:  It is the 21st of July and so far,  the JB turnout this year is less than what we had last year.  Maybe we can also try the milky spore method this year.